UNIT 3 4A: The Role of enzymes Flashcards
Substrate
A molecule that binds to the active site of an enzyme and then takes part in a reaction; also referred to as a reactant
What is a biochemical pathway (simplified)
A biochemical pathway involves a series of reactions, each catalysed by enzymes, where the product of one reaction is the substrate for the next reaction.
What is an advantage of a biochemical pathway
An advantage and key feature of biochemical pathways is that they are often able to regulate themselves
How do biochemical pathways regulate themselves
Generally, this happens through one of the final products inhibiting the function of one of the earlier enzymes in the pathway.This is an example of a negative feedback loop.
Catalyst
A substance that increases the rate of a reaction by lowering the activation energy and providing an alternative reaction pathway.
Activation Energy
The minimum amount of energy required to proceed
Active site
The region of an enzyme where the substrate binds for a chemical reaction to take place
Catabolic
Describes a type of chemical reaction that releases energy and involves breaking down molecules into simpler components
Anabolic
Describes a type of chemical reaction that requires energy and involves constructing molecules from simpler components
Allosteric site
A binding site on an enzyme, where molecules other than the substrate may bind
How is the specificity of the enzyme determined
The specific amino acid residues found in the active site help determine the specifity of the enzyme, through having R groups that will only interact and bind with the substrate.
What are the 2 different models for Enzyme-substrate interactions
- Lock and Key model
- Induced fit model
What is the lock and key model
This mechanism describes the situation where the shape of the substrate is a perfect fit for the unique shape of the active site of the enzyme.
What is the Induced fit model
Initially, the substrate is able to bind to the active site of the enzyme, as the two have complementary shapes and charges.
In contrast to the lock and key model, the initial conformation of the active site is not a perfect fit for the substrate.
Coenzyme
An organic, non-protein molecule that contains carbon and binds to enzymes to help them to function.
